dt-bindings: display: panel: use spi-peripheral-props.yaml

For devices connectable by SPI bus (e.g. already using
"spi-max-frequency" property), reference the "spi-peripheral-props.yaml"
schema to allow using all SPI device properties, even these which device
bindings author did not tried yet.

Change "additionalProperties" to "unevaluatedProperties", so the actual
other properties from "spi-peripheral-props.yaml" can be used.  This has
additional impact of allowing also other properties from
panel-common.yaml to be used.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20221004120907.72767-1-krzysztof.kozlowski@linaro.org


Signed-off-by: Rob Herring <robh@kernel.org>